German researchers use stereolithography to 3D print tiny glass structures at low temperatures

Apr 20, 2017 | By Benedict

Researchers in Germany have found a way to 3D print glass at relatively low temperatures. By mixing glass powder with a photosensitive polymer, the researchers were able to print detailed glass structures (including a glass pretzel) using an ordinary stereolithography (SLA) 3D printer.

From windows to camera lenses to sunglasses, glass is an important part of modern life. The material is hard, lasts a long time, and is—of course—transparent, making it suitable for a variety of applications.

Unfortunately, glass products being useful doesn’t make the material any easier to work with, especially where new manufacturing methods are concerned. 3D printing, for example, has so far struggled to make practical use of glass, largely because the material only melts at very high temperatures.

But despite the hard-to-print nature of glass, researchers in Germany seem to have shattered the material’s “glass ceiling”—by 3D printing the material on a standard SLA 3D printer. Their research paper, “Three-dimensional printing of transparent fused silica glass,” has been published in the journal Nature.

The 10 researchers on the study are all based at the Karlsruhe Institute of Technology (KIT), and are spread across the Institute of Microstructure Technology (IMT), Institute for Applied Materials (IAM), and Institute for Nuclear Waste Disposal (INE). They are Frederik Kotz, Karl Arnold, Werner Bauer, Dieter Schild, Nico Keller, Kai Sachsenheimer, Tobias M. Nargang, Christiane Richter, Dorothea Helmer, and Bastian E. Rapp.

“This work widens the choice of materials for 3D printing, enabling the creation of arbitrary macro- and microstructures in fused silica glass for many applications in both industry and academia,” the researchers say.

Interestingly, the secret to the new glass 3D printing technique does not involve making the SLA 3D printer print at higher temperatures. (High temperatures are still required, but not until after the 3D printing is done.)

Instead, the scientists have found a way to mix glass powders with easily 3D printable liquid polymers. Being photosensitive, these polymers can be 3D printed in the usual way on an SLA 3D printer, after which the special mixture undergoes a heat treatment process to fuse the glass particles together and make them transparent.

Although 3D printing with glass has been achieved before—Israeli 3D printing company Micron3DP appears to be leading the way in ultra-high-temp glass 3D printing technology—the German scientists say that their research could be the first example of glass 3D printing being carried out at regular 3D printing temperatures on regular 3D printers.

This, excitingly, presents an opportunity for other scientists to start 3D printing with glass on affordable 3D printing equipment.

To demonstrate the efficacy of their glass 3D printing technique, the researchers printed a number of detailed objects, including a tiny castle, a honeycomb structure, and even a glass pretzel—far from edible, but undoubtedly an impressive feat of engineering.

These small 3D printed objects have features as small as a few tens of micrometers, and this level of detail is only limited by the quality of the SLA 3D printer used. With a better 3D printer on hand, the researchers say that the process could be even more precise. The printed objects can also withstand temperatures as high as 800°C.

The researchers also say that their 3D printed glass objects can be made in different colors—by adding metal salts to the mixture before printing. This, coupled with the design flexibility afforded by SLA 3D printers, could enable users to 3D print a multitude of useful objects in glass.

It could be a long, long time before 3D printing replaces techniques like glass blowing, but these researchers have certainly shattered preconceptions about 3D printing with glass.